Looking for more memory.

You can upgrade your Ram. Ram does come in different memory amounts so if you have 4GB you probably have 2 sticks of 2GB you may want to look into getting 2 Sticks of 4GB each to make you 8 GB. Please make sure you know what your doing before you cracking open your case. 

Memory Type: DDR3 PC3-12800, DDR3 PC3-10600, DDR3 (non-ECC)
Maximum Memory: 16GB
Slots: 4
Although the memory can be installed one module at a time, the best performance comes from using matched pairs of modules

To get your computer ready, you need to make it safe. That means turning off the switch on the back of the power supply unit and Unplug the computer from the power source. Since your problably going to unplug all the cables to be able to open the case unplug the power cable. 

Once you've done this, you can sigh a deep breath of relief - you've circumvented the most dangerous aspect of installing RAM - electricity.

While working inside your case, be mindful of static electricity. To avoid building up a static charge that could potentially short out a component, some people use an anti-static strap to ground themselves (available from most computer hardware retailers). Or remember to touch a grounded metal surface from time to time to prevent a static charge from building. Touching your computer's power supply unit (provided it remains plugged in and turned off) should do the trick.