How to put in a flower bed???

[Youngster]

My aunt has asked me to do some work for her, and one of the things is to put her in a couple flower beds. Whats the best way to do it? I know i gotta dig up the grass. What is best way to keep weeds out? What kinda mulch/soil should i use? I guess if you could list you step by step way it would really help! I would like to thank everyone in advance! I really appreciate your help!

Youngster