I'll waste no time, here's how to install ubuntu alongside windows. But first things first, because i myself are using HP, i gotta warn you that there are some laptops who have been partitioned quite a few times by its manufacturer which will cause it almost impossible to install another OS alongside it, and unfortunately i gotta say HP is one of them. They did this in purpose so that you can only have one OS on it. But, fortunately i have broken this obstacle and successfully installed another OS on my HP laptop.

Here's how you do it:
1). Access your Computer Management by going through Start in windows and type in computer management, then on the left hand side scroll down to disk management / drive, click on it to show all partitions on your computer on the right hand side.
2). Right click on your C: drive or the one you want to shrink and select shrink volume
More about → How To Install Ubuntu Alongside Windows (7)

Here's how you do it:
1). Access your Computer Management by going through Start in windows and type in computer management, then on the left hand side scroll down to disk management / drive, click on it to show all partitions on your computer on the right hand side.
2). Right click on your C: drive or the one you want to shrink and select shrink volume