-Post them on http://www.soartex.net/forums/all-mods.27/

Or directly:

This requires moderate git/Github knowledge; if you need any help, feel free to contact us.

• Fork this repo to your account.
• Commit all of your textures to your forked repo, in the master branch. Preferably use as few commits as possible; if you experienced in git, squash all of your commits into one.
• Please include the version of the mod you was testing against. For example "ComputerCraft: Version - 1.56" This way we can ensure that the texture's are up to date.
• Open a pull request from your repo to this one with a clear and concise title stating what has been changed.
• Wait for a someone from Soartex to either merge or decline your pull request.
• If your pull request cannot be automatically merged, we will contact you and arrange manually merging it.
• When your request has been either merged or declined, delete you fork, and reform when necessary. This is to make sure you have the latest version of the repo when you commit your changes.