Do you mean Minecraft Forge 1.3? If so you are out of luck.
This version is not supported anymore by Forge Support, in fact before you make a support ticket you should have read the EAQ post at the very top of the list of topics. Forge Support team fades out support for older Forge versions. At the top of this page too there is a section for current supported versions and LTS versions (currently as of writing the LTS versions are 1.17.1 and 1.16.5). Failure to follow this is against the rules and will get you a warning and eventually a ban if you continue.
If you want support for unsupported version you should post on Minecraft Forums, it has a large community of people that will help you. Also if you do ask there you should specify the specific problem you have, and if your game is crashing you should supply a crash log. Minecraft 1.3 is a very old version, so support for it exists but not in massive quantity because of how old it is.