How can I visualize my md files on the VMD? and which files should I use?

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I want to visualize my xtc and start pdf from MD simulations. I could not understand how can I obtain start.pdb which options should be choose after these script :" gmx trjconv -s md_0_10.tpr -f md_0_10_center.xtc -o start.pdb -dump 0" and which type of files extensions will be used while visualize on VMD.