In my opinion both of the above sentences are incorrect.
(1) the verb 'have' is incorrectly used; it's a relative clause ('which') and needs an explicit subject ('something has four black lines');
(2) is grammatically better, but still sounds a bit awkward.
Using 'totally', do you mean there are four black lines in total? Since they are split in two groups, it is enough to say:
In the middle is a blue pattern with two black lines above and below (it).
'it' at the end of the sentence is optional, in my opinion.
In a description like this 'below' sounds better than 'under'.
Please note the inversion in the above sentence (the S + V + O principle would make it 'A blue pattern is in the middle...' or at least ('There is a blue pattern in the middle...'). However, the structure 'In the middle is a blue pattern...' is possible and frequently used in very formal written English, e.g. technical texts, instruction manuals, etc.