Ellen, there are two very different kinds of things that are both (confusingly) named Chrome.
- The Chrome browser is a google product that is a program. It can run on any kind of computer. There are many different types of browsers, but all do the same thing - you use a browser to go to websites, like WikiTree, for example.
- The Chrome operating system is also a google product, but it is what makes a computer run. A computer that uses the Chrome operating system is called a Chromebook. It has all its own programs built in and you don't need to install any software to use it, but its use is limited. It is mainly intended to use the internet for email and websites.
I am going to guess that you are talking about a Chromebook. Philip is correct about how gedcom files are made, but I believe he is assuming that you are talking about the Chrome browser.
You don't "create" a gedcom file on your computer. As Philip said, if you have your family tree on any website (or on a family tree program that you installed on your own computer, if it's not a Chromebook) then it will have a way that you can download a gedcom file. That is how you would get a gedcom file on your computer.
When you have a gedcom file on your computer, you can then upload it to a genealogy website (or import it to a family tree program if you have one on your own computer).
You cannot create a gedcom file on your own and there is no such thing as a "SHEET" or a "GED" that could "speak" to each other. I believe you are talking about downloading a gedcom file from one family tree website and uploading it to another one in order to move your family tree from one place to another. Please let me know if my assumption is wrong.