Welcome to the Forum!
This is what this board will support:
Four 240-pin DDR3 SDRAM Dual Inline Memory Module (DIMM) sockets
Support for DDR3 1333 /1066 MHz DIMMs
Support for up to 16 GB of system memoryhttp://www.intel.com/products/desktop/motherboards/DH55TC/DH55TC-overview.htm
I suggest either 8 GBs or 12 GBs (4 modules) depending on your computer use. I personally prefer Corsair products for good quality and great support.
Read specs and take your pick from here: http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007611%2050001459%20600006050&IsNodeId=1&name=240-Pin%20DDR3%20SDRAM