Hold the alt key down, and use your number pad (on the right-hand side of your keyboard). Here are some
of the common ones to get you started:

ALT+0134 = Bomb

ALT+0135 = 'No entry' sign

ALT+0135 = Stop sign

ALT+0145 = Black padlock

ALT+0151 = Double musical notes

ALT+0153 = ? symbol

ALT+0169 = Copyright symbol

ALT+0174 = Right Reserved symbol

ALT+0204 = White padlock

ALT+0213 = Diamond

ALT+0216 = Dashed

ALT+0245 = Spade

ALT+124 = White heart

ALT+130 = Dashed

ALT+141 = Spiral

ALT+156 = Pound

ALT+157 = White star

ALT+159 = Black heart

ALT+161 = Single musical note

ALT+167 = Lighting bolt

ALT+168 = ¡ symbol

ALT+169 = fish

ALT+173 = ¿ symbol

ALT+175 = Club

ALT+21 = Peculiar

ALT+230 = Coffee cup

ALT+241 = Mobile/cell phone

ALT+246 = Thumbs down

ALT+248 = ° symbol

ALT+249 = Thumbs up

ALT+271 = Euro sign

ALT+276 = Light bulb

ALT+422 = Skull

ALT+424 = Upside down

ALT+667 = Cent symbol

ALT0176 = Superscript

Shift+ \ = Heart

Doorblocking is when your Hablog character stands in the doorway and blocks other Hablogs from entering the room.