FASTQ is your raw data...
if you want to "visualize" (I think you mean you want to do something called variant calling and annotation afterwards) you need an adapter trimming first, then your reads in the FASTQ file are aligned against a reference genome (e.g. BWA) - so your input is a FASTQ file and your output file is a BAM file. The BAM file is then used by whatever software you use, to do a process called variant calling. So the output file here is a VCF file (VCF stands for Variant Call Format) - you got it now? this file is at the very end of your process...
Then get yourself a variant calling tool where you can simply upload the VCF file and set the filters that you want...e.g. variant allele frequency >5%, set your frequencies for ExAC, gnomad etc.. then you end up with some variants that you can now annotate and "visualize"!
hope that helps you a little bit....actually your post is 4 years old so I hope you learned something in that time!
(Slightly redacted by WouterDeCoster to remove inappropriate language)
I'll go ahead and assume you have no experience at all with analyzing NGS data?
Well, your question is a rather long story. You'll first some quality control, adapter trimming, read mapping and variant calling to get a VCF file.
Also, you didn't specify anything about which technology, which organism or what the to be obtained result should be.
Is there someone in your institute who can help you?
Start by reading beginning chapters in this book (and then chapter 6) to get a grasp of the task at hand that you have described in one sentence above (like @Wouter I am assuming some things). Then come back and flesh out the question with additional details so people can give you directional guidance.
You may be a computer scientist well versed with command line or a biologist who is a novice at command line. Depending on which category you are in the subsequent ride can be wild or a bit less so.