“Guys, help me straighten up a little please.”

Your sister and her family are coming over to your house to visit. Your living room is a little messy. You ask your children to help you clean it:

Guys, help me straighten up a little please.

Guys

In English, there's not a really good word for addressing a group of people. In different parts of the country, people use different expressions when talking to a group. The expression I suggest is "guys". For example, you can say this to your parents:

Guys, I have to talk to you.

You can say this to the members of a girls' sports team:

Great job today, guys. Keep up the good work.

"Guy" technically means a man, but it's usually OK to use it for groups of males and females, or even for groups of all femaies. 

Help me (do something) please

This is a very straightforward way of asking for help. Use this when you're speaking to someone you're close to, like a family member. Avoid asking strangers and friends for help this way. A better way to ask is:

Could you help me with this?

Adding "please" to the end of your request actually makes it sound a little less polite in this case. Here are some other examples of "please" used in an angry or impolite way:

Can you wipe that up, please?

Can you just stop it please?

straighten up (a room)

"Straightening up" is a type of cleaning. When you "straighten up", you pick up things that are lying around like clothes, dishes, books, pieces of paper, and so on. You put things back in their proper place, so that the room looks organized.

You can use "straighten up" with an object:

Lance, straighten up your room please.

Or you can use it without an object:

Sorry, I didn't have time to straighten up.