Drawing and Naming groups with cis and trans

What I know so far, is Alkenes contain a double bond and wherever the double bond is, requires a number to specify its location.
2-Butene for example would have a double bond its second carbon bond.
If we add a substituent to the third carbon. Methyl for example.
This would be 3-methyl-2-butene as the side group takes priority when naming.
I hope I am correct so far. This is the same with halogens. I would number their location, too.
When it comes to cis and trans. I am extremely confused.
I saw that for cis, the two alkyl groups must be on the same side, and for trans, they should be on opposite sides.
If let's say I introduce the halogen, chlorine.
In the chemical cis-2-chloro-2-butene.
If I have two ch3 substiuent, why is this no longer Di-methyl? None of the material i have explains this? Also, what if I draw it in long compound form? Does this remain cis or become Di-Methyl?
I shall attach what I have drawn.

I believe if you put a methyl group on the “third” carbon of but-2-ene, that carbon would end up becoming the second carbon in the chain (so as to give all groups the smallest possible numbers) and so you would have 2-methylbut-2-ene (or 2-methyl-2-butene).
I take your question to mean what if we put methyl groups on carbons 2 and 3 of but-2-ene. If you were to do that, it would be 2,3-dimethylbut-2-ene (or 2,3-dimethyl-2-butene). As the -CH3 groups are identical to one another, assigning E/Z or cis/trans configurations isn’t possible. You need both carbons in the C=C bond to have two different groups bonded to them for there to be some form of geometric isomerism.

I’m glad you could decipher what I meant lol. So, cis and trans can exist only in double covalent bonds. In alkanes containing single bonds, di, tri, etc., exist.
Have I drawn the molecule correctly above? For cis-2-chloro-2-butene?

Alkanes cannot be cis/trans etc because there is free rotation about the C-C bond, allowing them to interconvert between what would apparently be “cis” or “trans”. As such, they are not recognised as distinct isomers, but rather different “conformations” (you will have these explained to you later down the line).
If there is not free rotation (i.e about a C=C bond or within a ring), cis/trans isomerism may be possible. It depends a lot on what groups there are.