I applied using the new portal :
Sign in (cic.gc.ca)
Just upload all the documents they ask for, its all digital.
In the additional documents I included stuff like, letter of invitation, explanation of dual intent, info connecting to my spousal application, marriage certification, my cad citizenship card etc
For proof of funds i showed my own bank accounts and a job letter showing how much income i make, CRA tax assessment. (I only showed them like $8k so)
for the letter of invitation i followed the websites guidance exactly.
keep everything clear and concise
I selected atleast 6 months. for travel dates i said sept-jan, (but in the purpose of travel letter i asked for more time if possible)
let me know if u have any questions