It sounds like you are wanting to learn the general how to prepare a tax return for a self employed person, rather than how to use the software for it.  Is that correct?

If so, reading IRS Publication 334 is very important.  Don't hurry through it; take your time and understand what it is saying, even if you need to read it multiple times.  Also, read the Instructions for Schedule C and Schedule SE.

After reading those, if you have any specific questions about something, feel free to come back and ask.

And when you are preparing a self employed client's tax return, if you are unsure of something, don't just guess.  First, research it it (Publication 334 and Google are great), and if you still are unsure, you can come back to a forum and ask any specific questions.

https://www.irs.gov/pub/irs-pdf/p334.pdf

https://www.irs.gov/pub/irs-pdf/i1040sse.pdf

https://www.irs.gov/pub/irs-pdf/i1040sc.pdf