To play Minecraft with mods you will need to install Forge. Most people think this is hard to do, not so. It is very simple and in less than 5 minutes you can be playing Modded Minecraft.
Just watch the video below or follow the steps listed below.
Download the required Forge version from the download site :
Click on the downloaded jar file to activate the installation process.
Select client install and click ok.
Open your Minecraft launcher and click "New Profile". Name it something memorable and then select Forge 1.7.10 from the version drop down. Click save.
Make sure you select your new profile and click Play.