how to change the resolution of fedora ?

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http://forums.fedoraforum.org – Today I downloaded Fedora 9 (sulphur )and its working fine , I am using it on core 2 duo with AMD processor and 15'' LG monitor . But its showing only resolution that is 640x480 ,so due to this having problem to use the system so can any give me solution that how can change the resolution from 640x480 to 1024x768 . (HowTos)