Hi @jingamells and welcome! Looks like there are a couple little things here. First, is that when you use install.packages(), you need to put the the name of the package in quotes ("package_name"). The other thing is that there is a package called XML and a package called xml2. I'm not sure which package you are intending to use, but you could install them both by running:
install.packages(c("XML", "xml2"))