Letter of invitation for canada.....need some assistance

Wish to invite a longtime friend to visit Canada this summer. What i do know is i must take the letter to a lawyer before sending it but what advice i'm seeking is how to construct the letter properly. what should i have in it other than the general invitation. i want to make sure everyting proper . thx in advance for your help

https://www.canada.ca/en/immigration...nvitation.html

Thanks rasta. Just what i needed