That’s a great goal. Like every goal, you should start small and have a plan. Regarding nutrition, there are several strategies on how to gain weight, but I will only talk about the two most common:

Dirty bulk: eat more than you usually do without really watching your caloric intake and what time of food you’re eating. People usually eat junk food. That will make you gain weight (not recommended).

Clean bulk: eat more than you usually do by slowly increasing your caloric intake and eating primarily healthy foods.

For example: increase your daily caloric intake of 300 kcal, then the week after you weigh yourself and see if there is any difference.

If there is no difference, increase your caloric intake of 150 kcal, then repeat the process the week after.

If there is a difference, keep this daily caloric intake and see if you maintain that weight the week after. If you maintain, go to step 1 and repeat the process.

I highly recommend you to take the second approach, it will help you build healthy habits on the long run. Take one day where you measure everything you eat and see your daily caloric intake. Then go from there. Then when you have that number, you don’t have the measure everything all time. You will roughly know where you’re at and you can increase it.

It might be a lot of information to absorb right now, but you can take a look at this article I explain how to train and eat according to your body type. You seem to be an ectomorph, check it out:

https://www.gymaholic.co/articles/eat-and-train-according-to-your-body-type

Hope this helps.