Abut conceiveing a bby?

sum ppl say when u conceive yes u do get preg sum ppl say the day u conceive is the day the bby is made tooo sum ppl say no it take 1-3days 1-3weeks thats wut confuse ppl and than sum ppl are lik oh lord can u feed a bby no its just a lot of confuseing so wut is it lik me by a u/s my dr said i had a lmp july,16 2010 and i check on the computer my most fertil days was frm july,27-aug,1 sum says u are fertil 5days 6days 7days are 9days am sooo confused