Why Is My Computer Running Slow

3-4 questions about Linux, some email questions, determining the age of a web page, Slow Computer Disease (SCD), downloading question and more!

My sister has her own email address through an extra computer she has at home that she uses as a server. I would like to do this but don’t know how. I have cable internet and an extra computer that is realy slow but should work as an email server. It would be cool to have my own email address so any thoughts would help!