It will depend on the devices. Most VCRs will have composite and S-video outputs. For this you will need either a composite audio/video cable (3 RCA plugs on each end: yellow (video) and red and white (audio)) or an S-video cable and a separate audio cable. The DVD player will probably have component video or HDMI outputs, depending on its age. The component video requires a 3 plug RCA video cable (red, green, blue) and a 2 plug RCA audio cable (red and white). Some DVD players have composite outputs as well. However, this limits you to an SD video output and isn't recommended, unless your TV doesn't have any HD inputs.
If your TV has one each of the appropriate input ports or 2 composite video ports, you just need those cables, assuming you have no other devices that have filled the inputs. Always connect the devices with the TV and the A/V components off. Match the color of the plug to the port. If you mix up the colors on component video cable, you may get a black&white picture. Some newer TVs use an adapter dongle to convert composite or component video to single port on the input board. Again match the colors at the dongle and then plug in the adapter. If your TV has shared composite and component signals, use the HDMI port output on the DVD player, if possible, or get a Audio/Video switch, like this: http://www.amazon.com/Panlong-Switcher-Composite-Selector-Consoles/dp/B00KXVBB3Q/ref=sr_1_24?s=audio-video-accessories&ie=UTF8&qid=1440632814&sr=1-24
Please add a comment with the make and model of your specific TV, VCR and DVD player. I hope this helps.