I just started playing yesterday and have built a small fortress under ground, I want to make a stockpile for wood there near the Carpenters workshop but there are rocks there and it blocks parts of it how do I make someone pick up the rocks?
Dwarves won't pick anything up unless they have a job to do with it. Either assign a task in a mason's workshop to use up the stone or designate a stone stockpile.
Since you're new, fun fact: Food stockpiles are necessary to prevent decay. Food will slowly rot when left to sit just any old place. Raw meat will very slowly (over the course of 2 years or so) decay even in a stockpile, so be sure to cook any meat.
And how do I populate other dwarfs?
Dwarves will occasionally become lovers and have children periodically, but the primary means of population growth is immigration. Fortress wealth and trade to the dwarven caravan (especially offerings) will increase immigration. Dwarf deaths will hurt immigration. Doing a lot of mining may also increase immigration.
How do I make them go down stairs and live there?
You need to designate a meeting zone. Check the zones menu (press 'I'). Alternately, designated certain types of rooms will attract idle dwarves (dining halls, statue gardens, zoos, and barracks).
How do I make someone work? I have a workplace but none works there .
You need to enable the appropriate labor before a dwarf will use a given workshop. If you want them to carve stone blocks and make stone furniture (in a mason's workshop), assign a dwarf to the masonry labor. Press 'V', select a dwarf, then press 'P' then 'L'. That'll bring you to the labor assignment screen.
WHY WON'T ANYONE MAKE THE FARM!? I HAVE A STINKIN FARM PLOT SET UP!!!
This is also a labor issue. You need to assign a dwarf to Farming (Plot) or whatever it's called. There's another farming labor called Farming (Workshop) or something to that effect. That lets them process plants in a farmer's workshop. You want the plot one enabled to make them build and tend a farm.
Wiki: http://www.dwarffortresswiki.net/index.php/Frequently_Asked_Questions
You see this? This is your friend. Aside from the forum, the wiki is the best info source available for DF.