What Are The Uses And Side Effects Of Marvelon 28 Pills?

ive been taking althea pills for 6 months and i changed my pill to marvelon 28..does it have the same dosage or should i get the same effect as althea pill. and i also have one concern, i missed 1 pill and forgot to take it within 24 hours, and what i did is i took 2 pills at the same time..is it correct? and my husband and i had sex after 4 days..is it safe?thanks.