Apache help

i have apache on my computer but need help letting people get to it
iv been googling for apache help for a few days and i have a few questions that i cant find the answers to a few questions

when im on a different computer what do i type on the address bar for my site? iv tryed my ip address and

how safe is the rest of my computer when apache is running online?

im on wireless internet, but have the router and modem plugged into another computer in my room, do i need to mess with any of this stuff?