Welcome to the Community! It's great to see new faces and members.
I can see you are interested in making signatures. I've also noticed you posted in a Design Team applicants thread. There are rules that the Design Team has set up, and one of them is you must be the applicant or a design team member to post in the applications thread.
If you wish to join, please read the rules and post. Also, to answer your question, Deviantart.com and youtube, have some really good signature tutorials that you can use to help yourself get better. If you don't mind, what program do you use to make pictures?