You can always help out by testing your games in Dolphin. Look up known issues on the Dolphin Wiki and verify whether or not they still exist when using the latest development revisions. If something gets fixed, you can notify someone right away to get the page updated. If you discover a new issue or a regression, you can also report that. When reporting issues, it's best to collect as much information about the bug as possible and double-check everything (e.g. double-check that the behavior on a real Gamecube/Wii differs from Dolphin, double-check that the bug is reproducible, double-check any relevant settings that may have caused the issue).
Besides that, you can help out around the forums as well, answering questions and such. Some times providing genuine help and support on the forums requires being familiar with Dolphin for quite a while, but you can also give out tips for people selecting new hardware as a start (e.g. sharing with others your experience with your past or current hardware setups).
EDIT - Also, consider upgrading to a more recent version of Dolphin if you want to help test things. 3.5-xxx is years old and not supported anymore.
Besides that, you can help out around the forums as well, answering questions and such. Some times providing genuine help and support on the forums requires being familiar with Dolphin for quite a while, but you can also give out tips for people selecting new hardware as a start (e.g. sharing with others your experience with your past or current hardware setups).
EDIT - Also, consider upgrading to a more recent version of Dolphin if you want to help test things. 3.5-xxx is years old and not supported anymore.