how do i make arches using hammer?

When in brush mode, select Arch under object, over on the right.

yeah, kinda the bottem right. right now in sais block (probally) and scrool down to arch

thx guys

still cant see this ever elusive arch tool

ok, on the right hand side of your screen should be severla panels.
On of the will have 2 buttons in the top right, To world and To entity. This is the panel you want.

Make sure the top drop down menu says Primitves, go to the one below it and select Arch form the tool box. drag a box hit enter, play with the options that appear.