Talking about things that will happen in the future is easy, you just speak the same way as if you were speaking about the present. The listener can see whether you’re actually talking about the present or the future from the context.
- Ég elda spagettí. = I cook spaghetti.
- Ég elda spagettí þegar ég kem heim á eftir. = I will cook spaghetti when I come home later today.
- Ég fer í sund. = I go swimming.
- Ég fer í sund um helgina. = I will go swimming next weekend.
Verður = will be / becomes
The only exception to the simple explanation above is that you use að vera (to be) when speaking about the present, but you use a different word, að verða (to become), when speaking about the future.
- Ég er upptekinn.
- Ég verð upptekinn.
- Þetta er mjög skemmtilegt.
- Þetta verður mjög skemmtilegt.
Mun (will be)
There does exist one other way to speak about the future, using mun (will):
- Þetta mun aldrei virka. = This will never work.
- Same as Þetta virkar aldrei.
- Ég mun sjá þig aftur. = I will see you again.
- Same as Ég sé þig aftur.
- Þú munt aldrei verða ríkur. = You will never become rich.
- Same as Þú verður aldrei ríkur.
However, you never actually need to use it, you can always just word your sentence in a way that just uses the present tense. As a student, you should recognize this word but you should not use it yourself when speaking. The reason for that is that learners tend to use it in situations where the present tense would have sounded much more natural.