Your return should be a fairly straight forward affair in that case.
If you haven’t yet got a TIN (tax reference number aka Numéro fiscal) you can obtain one from the tax office which will allow you to file online. Time is running short for declarations on paper but the forms can be downloaded from the Fisc - but this reference may be useful in the meant time.
Also will be of help is for you to read through my guide on completing your tax return (on line) which will cover much of the paper submission in your case as well.
The task isn’t as onerous as it might seem at first glance. Take your time to read through the posts and those in this topic too.
If you have more questions, post them in the topic started by @Stella (the second SF link I provided) and tag me with @ if you feel I can be of further help.