[First time installing forge]

so i just installed forge and everytime i launch it, it crashes please help me im using 1.8.9 version of minecraft and forge version is 11.15.1.2318 ps I have no clue on what any of this means. here is the crash report:

---- Minecraft Crash Report ----

WARNING: coremods are present:
Contact their authors BEFORE contacting forge

// But it works on my machine.

Time: 11/18/19 7:59 PM
Description: Initializing game

java.lang.NoClassDefFoundError: cer
    at java.lang.Class.getDeclaredFields0(Native Method)
    at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
    at java.lang.Class.getField0(Class.java:2975)
    at java.lang.Class.getField(Class.java:1701)
    at net.minecraftforge.fml.client.FMLClientHandler.detectOptifine(FMLClientHandler.java:277)
    at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:191)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:417)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:329)
    at net.minecraft.client.main.Main.main(SourceFile:124)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: cer
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more
Caused by: java.lang.NullPointerException
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)
    ... 17 more

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
    at java.lang.Class.getDeclaredFields0(Native Method)
    at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
    at java.lang.Class.getField0(Class.java:2975)
    at java.lang.Class.getField(Class.java:1701)
    at net.minecraftforge.fml.client.FMLClientHandler.detectOptifine(FMLClientHandler.java:277)
    at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:191)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:417)

-- Initialization --
Details:
Stacktrace:
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:329)
    at net.minecraft.client.main.Main.main(SourceFile:124)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
    Minecraft Version: 1.8.9
    Operating System: Windows 10 (amd64) version 10.0
    Java Version: 1.8.0_51, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 545781064 bytes (520 MB) / 771751936 bytes (736 MB) up to 1073741824 bytes (1024 MB)
    JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M -Xmx1024M
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: 
    Loaded coremods (and transformers): 
    Launched Version: 1.8.9-forge1.8.9-11.15.1.2318-1.8.9
    LWJGL: 2.9.4
    OpenGL: GeForce GTX 960/PCIe/SSE2 GL version 4.6.0 NVIDIA 436.30, NVIDIA Corporation
    GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

    Using VBOs: Yes
    Is Modded: Definitely; Client brand changed to 'fml,forge'
    Type: Client (map_client.txt)
    Resource Packs: vanilla
    Current Language: ~~ERROR~~ NullPointerException: null
    Profiler Position: N/A (disabled)
    CPU: 4x Intel(R) Core(TM) i3-4160 CPU @ 3.60GHz