Hello, lets try to understand the idioms. The meaning of idioms is quite different than the actual meaning of words used.
Roll up your sleeves means to get to work. It also means readiness to take on the task. We can easily visualize this. It happens in our day today life. Suppose we are wearing a shirt with full sleeves and we are about to lift something which is heavy, we roll up / pull up our sleeves first and then lift..Ex -guys, roll up your sleeves to practice better Englishh.
This idiom can also be written as `to roll up one's sleeves` in phrase form. Any phrase with one's in it, this `one's` is replaced by my,his, her, our, your, their etc. ex- I saw no one was coming forward to solve the problem, so i rolled up my sleeves and started working on it.
so, pull up your sleeves now to write comment on this.