Diant,
I know you asked how to conceal acne, but you should concentrate on healing them first.
Have you tried different acne solutions? I know some people just have such bad acne they actually need the strong perscription stuff like Proactive. I hear that is expensive though, and for the worst acne... you have to watch your skin exposure to sun, be on birth control...etc. I am not positive of this..but its what I hear. If your acne is bad enough, you may want to look into talking to your doctor about prescription methods
I like to use Neutrogena, I have grown up with it and I depend on it completely. I use the Body Soap as well as the Rapid Clear treatment pads. The pads work great for wen you see a break out happening. They help stop breakouts and reduces them over night!
Now for when I do get pimples and dont want them to be as noticeable I actually use a nice makeup line called Bare Minerals. Its rather expensive, but very good for the skin since it is made of all natural minerals and its so mild on your skin you can sleep in it and not feel dirty...as I always felt when using other liquid concealers. Bare Minerals is all loose powders that do SO well at concealing and blending my skin. I will never go back to liquids or compacts.
Now I know you might not be able to afford the money to be buying expensive stuff, so why dont you try and go to the mall and ask one of the sales ladies at the make up counters to give you ideas of concealer for your complexion?
I used to use the liquid concealers on the pimples then use a compact powder to blend it all in, but looking back I dont think it did very good...haha.
I wish I could give you better tips... I know its so embarrassing to have pimples you cant hide.
if you would like to look into those products I mentioned, here are the links. Best Wishes!
Neutrogena Official Website: Neutrogena.ca - Dermatologist Recommended (http://www.neutrogena.ca/en/index.asp)
I like to buy my products here though: drugstore.com Online Pharmacy - Prescription Drugs, Health and Beauty, plus more (http://www.drugstore.com/)
They have a sister website for just beauty products: Shop at Beauty.com for Make Up, Cosmetics, Skin Care, Hair Supplies + Tips and Secrets (http://www.drugstore.com/templates/notcoldept/default.asp?catid=9730)
They both have so many great products and sales. You can see reviews from other customers and decide if you want to try something else.
Bare Minerals http://www.bareminerals.com/