Here is a good site for graphing half-planes.
http://hotmath.com/help/gt/genericalg1/section_4_4.html
This is an interactive site which will graph half-planes.
Write the given inequality in the form
Ax + By < C
or
Ax + By > C
with the inputs on the other row zeros.
If you want to graph an inequality with equality included, then draw the boundary solid rather than the shown dashed boundary.