The severity of acne dictates the choice of treatment. In the early grades of acne even the cream might suffice however in moderate to higher grades tablets also need to be taken. The treatment has to be continued for a few months otherwise the pimples would tend to return easily. Kindly do not self medicate without professional advice as that could further damage your skin. For the black marks you can try applying kojic cream for a month which will decrease the pigmentation on the marks. Get an online consult privately with pictures or meet a dermatologist directly for a proper evaluation of the condition. Hope this was helpful.