Thanks
I already solved this, and its pretty simple.
-> First login arcgis.com and in your profile , create your map.
->Map->Name it and everything.
->Then in the section "ADD" add a layer from file, and the excel where you have the data, convert it as CSV, make sure you are in windows when you upload it, because I was on OSX and it gets me an error.
-Thats all, you can have it with coordinates or with the names of the cities or municipality.
I got the info right here : Tutorial 2 Loading data into a new Webmap - YouTube
I hope It helps, Thank you!