You can start by taking what it says on face value, using simple sentence diagraming you were taught in elementary school and high school.
No offence, but that is a serious comment. If it says something that is an anology, then read it as such. Jesus told us to eat His flesh, but He was standing there, were we to kill him? Jesus also said He was a Shepherd yet no sheep followed him around; that He was a Door, where was His handle or the hinges?
But if it clearly says something as a fact, like all your sins are paid for on the Cross, then they are, that Mary had other children, then she did; ...