Entity tool, then search on the right side of the screen for an armory entity. Then when u put it in the map (best way is by 3d view), right click on it from a 2d view and choose the number of weapons spawned by that entity and the weapon itself.
Get Weapons when you spawn:
take the entity tool , search on your right side for game_ player_ equip , place it in your map (doesnt matter where). Now double click it and deactivate smart edit ( the button for that is in the upper right corner). you have to enter the weapon you want under "key:" e.g. weapon_deagle ; weapon_ak47 . When you did that you have to choose how many every player get when he spawn , by entering the number under "value:"
If you want 2 or more weapons you have to click add for every new weapon
A single weapon in your map:
Click on the entity tool and search for the weapon you want in the lower right corner ( every weapon will start with weapon_ . e.g. weapon_deagle). When you choosed the weapon click in the level where you want the weapon.
How to add ammo: deactivate smart edit , by clicking on the smart edit button in the higher right corner. after you did that enter "ammo" in the entry field , add so many ammo you want by entering the number in the entry field "value:"
take your nodraw texture and creat a brush with this texture where you want the buyzone. than select this brush and press Cntr/strg + T . Now write func_buyzone in the entry field . Choose a team who can use the buyzone by selecting "Terrorist" or "Counter-Terrorist" under "Team number (Int)"
I hope you understood my horrible english :(