How to make a fixed width of design

In case you don't want your design to stretch according to monitor size but rather leave some empty space from left and right sides, you need to open your CCS file where find such line:

.frameBlocks {margin: auto; padding: 0 20px 20px 20px; text-align: left;}

and change it for example like this:
.frameBlocks {margin: auto; padding: 0; text-align: left; width: 999px;}