How can connect a electric wire to a hanging light fixture using a cha

Find an electrician to do it for you.

PLEASE DO NOT TRY TO DO THIS YOURSELF - Electricity can kill !

An authorised electrician is the only way to go. You should NOT carry out this sort of maintenance yourself. It might very well negate your building and contents insurance, if there was a fire, etc..

Can't find it online but they used to make a socket that screws into a light socket. It has a chain pull on the side to turn it on and off. It has a place for bulb at one end and often a place to plug in for power to small appliances. As others said to change out whole light call an electrician. It's safer.

Are you talking about converting a light to a swag light?

https://www.youtube.com/watch?v=nb7Xmm3JBkA see my comment about hot wire and the right screw to attach too.

https://www.youtube.com/watch?v=jpdTG1-YJpM how to tie a UAL knot

brass screw to hot wire, smooth shealthing / rigid wire to neutral screw - silver screw.

conversion kit for ceiling fixture to swag.... https://www.youtube.com/watch?v=idzPpqWjck8

hook install... https://www.youtube.com/watch?v=NoEUviHbscU&t=290s screw end for screwing into wooden joist above, toggle bolt for drywall install - predrill hole big enough to fit folded toggle through.