IPv4 Packet Header

Thanks Rene for your reply.Please dont mistake me as i asking some of basic questions

I can understand the length of the IP header is 4 bits.but I am having a lot of confusion between bits and bytes calculation.

1bit==can be either 0 (or) 1

if its 4 bits then it should either 0101 if i convert that number from binary to decimal i get 5.

I am not sure whether my understanding is correct or not.please guide me Rene

IP header:

Here as you said 4bits and with that you can create value between 0 and 15. I want to know how these value are determined?

You say each bit represent a 32 bit increment

Total Length:

total length are 16 bits so we can store values from 0 - 65535 here.I want to know how these value are determined?

Fragment offset:

How fragment offset value 185,370,555 was determined?