You can't have the spotted reptans by cross-breeding! You only can have it in buying it or mutating a painted reptans or a spotted scandens, witch are difficult to obtain!!

and what does it look like? i thought i saw a guide as to what looks like what but i cant find it now

this is a spotted reptans:

is there a guide as to what each plant looks like?

what does a Fourpetal Reptans look like?

there is the borg's charts that Jazzo has converted in pdf format:
Borg's charts in PDF

How do i get a nox orchid from a tilia orchid i got from an extinct seed i bought?

you may have it in several step.
1- try to have a fourpetal or a blazing
2- try to have a rosaceae
and then you may have a nox

How can I make a spotted reptans? Please help me!

A Spotted Reptans cannot be bred from other plants. The cheapest way to obtain one is to buy one from the Supply Shop, since mutating plants is expensive and requires a lot of luck.