how do i use brackets

Brackets are used for many things.

Two common ways i know it's of use are:

1) Two separate information . 

      e.g. 3+4-6+5

       $${\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\mathtt{4}}{\mathtt{\,-\,}}{\mathtt{6}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{6}}$$

But if you want 7-11

Expanded can be (3+4)-(6+5)

The information is separated so that you/and the calculator doesn't get confused.

$$\left({\mathtt{3}}{\mathtt{\,\small\textbf+\,}}{\mathtt{4}}\right){\mathtt{\,-\,}}\left({\mathtt{6}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}}\right) = -{\mathtt{4}}$$

2) Another way is mainly used in algebra for multiplying.

E.g.    3(x+4) 

This also means (3*x) + (3*4)                   --> See how i used the first way of brackets there.

So i just showed you it expanded.

It = 3x + 12.

Also brackets is used in English for extra information (in scripts too) in writing.              <----  I used it there.