[RoDenT]

open up your console by pressing the '~' button. If your console is disabled, go into the options by pressing the 'Esc' key and click on options. Im not sure where the Developer's Console is in the options so search around for it and enable it. Then go back to the game and press the '~' button to open up your console. Type cl_showfps 1 and press enter. You can also type net_graph 1 or net_graph 2 or net_graph 3 to show your fps.