Hi, my question is that if we each have spefic DNA that is sgemented by chromosomes than how can we have, in our cells, different varations of our dna (paternal/Maternal) also known as homolgous chromosomes?

This is a good place to start, specifically crossover:
https://en.wikipedia.org/wiki/Meiosis

Different variations of our DNA exist within us since we actually have two copies of DNA, arranged in paired chromosomes. We get one of these from each parent. This arrangement occurs as humans are diploid organisms (sometimes written as 2n. Some other organisms, especially plants, are tetraploid, 4n, or more - tetraploid organisms have four copies of the DNA). This means we also have two versions of each gene, and we call these versions alleles. Roughly speaking one allele comes from each parent, though, like Reetika says, crossing over occurs which can chop and change parts of genes. Because genes only make up a fraction of our total genome, crossing over is more likely to occur in non coding regions, which is why it isn't completely wrong to say that you get one gene version (allele) from one parent.