“~ri” is used to indicate that you will / can do multiple things. This should be used to attach in past tense verbs.

Example :
Kaku (Write) – Kaita (Past Tense) = Kaitari

Q : Where wouldyou go during summer holiday? – Natsu yasumi ni wa doko e ikimasu ka?
A : I’ll go to sea and mountain – Umi e ittari, yama e ittari shimasu.
Meaning : Natsu (Summer), Yasumi (Holiday / Rest), Umi (Sea), Yama (Mountain)

Remember, the “~ri” used in tha last verb must be followed by “shimasu”

Q : What would you do on Sunday? – Nichiyōbi ni wa nani o shimasu ka?
A : Usually I will take a walk and read books – Taitei sanpo o shitari, hon o yondari shimasu
Meaning : Taitei (Usually), Sanpo (Take a Walk)

You may notice that a similarity with my previous lesson on the use of “~shi“. However “~shi” is used to define that you can do one thing and also another thing. In this case, “mo” is necessary when using “~shi”.

Hope this doesn’t confuse you. If you need futher clarifications, feel free to post your question here.