One of the ways the て form is useful, is that it can be used for making a request: that is, politely asking someone to do something.
This is really easy!
ほん means 'book.' よむ is the dictionary form of 'to read.' (When I say dictionary form, I mean literally the simplest form which is always found in the dictionary.) を is the particle that usually comes before verbs (I don't yet understand it to it's fullest extent.) Finally, the word we need is 'please,' to make it polite. This is ください。
Please read the book.
You need to change the verb into the て form for this. ほんをよむください。X Is not correct.
Now, as long as you know the object and the verb, you can ask politely for a person to do anything!
ビデオをみてください。Please watch the video.
うちにきてください。 Please come home.
Did you notice that in the second setence, the particle is に instead of を？ When you are suggesting a movement from A to B, you usually would use に instead of を.
That's all for now!