update readme with more instructions

README.md

@@ -2,3 +2,26 @@
 
 Install Vagrant, and run the VM with `vagrant up`!
 
+## Usage
+
+* Install Vagrant. If you are using Homebrew on macOS, just use `brew install vagrant`.
+* Clone this repo and `cd` into the directory.
+* Run `vagrant up`. This should set up your VM in a few minutes.
+* Run `vagrant ssh` in the directory to SSH into the VM.
+* If you need to copy files from/to the VM, you can use the vagrant-ssh plugin:
+  install with 
+      
+      vagrant plugin install vagrant-scp
+      
+  and then you can copy files to the VM:
+
+      vagrant scp local/path/to/file :remote/path/to/file
+
+  or from the VM: 
+
+      vagrant scp :remote/path/to/file local/path/to/file
+
+* To use VSCode with the Vagrant VM, first run `vagrant ssh-config` in the
+  repo's directory, and then append the output to your `~/.ssh/config` file.
+  You can rename the host as you like (change the first line to `Host mininet`).
+  Then in VSCode you can connect to the `mininet` host.