To begin your application process, it would be good to start contributing by means of meaningful pull requests to Jenkins to build up your portfolio, which you can use in your GSoC application (to be opened early next year). The best guide you can use is the
https://www.jenkins.io/
website. We have a Contributor Guide at
https://www.jenkins.io/participate/ which will be particularly relevant to you. If you have any coding questions you would like to ask during
this period leading up to the commencement of the GSoC application period, you can direct these to our Gitter channel dedicated to GSoC, or to any relevant Jenkins channels there. For more info on GSoC per se, please use
https://www.jenkins.io/projects/gsoc/ as
a reference. if you have any further questions please let us know.