step 1 point mortar toward target
step 2 crouch and use the 'fix bayonnet key' to deploy the mortar
step 3 open map and if you have SL arty mark , right click on it to select it
setp 3.5 insult all the SLs in teamchat to get a mortar mark ( Y is base key for team chat)
step 4 close your map and scroll up to open your mortar aiming stuff
step 5 use W S to set up your elevation according to the range table , Q and E to adjust left/right toward your target
step 6 shot some shells , wait about 15 seconds
step 7 get a triple TK
step 8 open map again , if you hit close to a selected arty mark , the splashes will show up on the map, adjust accordingly ( higher angle mean hit closer , lower angle mean hit further)
step 9 keep shooting