First of all, we are glad you are here! We welcome contributions and input from the community.
You can find guidelines on how to contribute to SimPEG in the Contributing to SimPEG section of our documentation.
All code contributed to SimPEG is licensed under the MIT license which allows open and commercial use and extension of SimPEG. If you did not write the code yourself, it is your responsibility to ensure that the existing license is compatible and included in the contributed files or you can obtain permission from the original author to relicense the code.