This is quite easy my friend. You can tell an item from a prop by the fact that items have tiny glowing, star like particles swirling around the item. If it doesn't have these particles, then it's a prop. The way to pick up an item is by clicking on the item and a button above the item will ask "Equip", click them and your character will rush over to the item and put it on them. If you can't seem to find it, you can go into a different camera setting by pressing f3 (Or alt and f3 at the same time) and you'll be able to control the camera the same way you would your character, but will be able to zoom in on items much easier, and you'll have an easier time to pick up smaller items. The way to get out of this camera mode is by pressing f2 (or alt and f2 at the same time). If you want to put items in, or finding items in, your stash, press "i", and it will bring up a popup with what you are wearing, just press stash to find items. Or, say you want to stash said item that you're wearing, just press the item and "stash", or if you don't want it, "drop" etc. If you have any other questions, feel free to ask.
~Saii ^-^
Seems solved then, PM me if you're still having problems.
//Locking!