I am not a Chinese native speaker, so there might be some mistakes in my sentences, but I do have some suggestions for you, because the way you put it, it is quite difficult to understand. And corrections by Chinese native speakers are greatly appreciated.
I have learnt a new Chinese character: popo
-> This character can have several meanings and it is more common to use it for referring to one's mother-in-law, rather than to your grandmother. The paternal grandmother is mostly called 奶奶(nainai) and the maternal grandmother 外婆(waipo) or 姥姥(laolao).
我要谈谈我的婆婆。I want to talk about my grandmother.
这个星期我跟她打电话了。This week I talked to her over the phone.
这个星期is more common. 她means "she".跟...打电话= talk with someone on the phone
她下山的时候摔倒了。When she descended a mountain, she slippend and fell.
下山=descend mountain, 的时候=when, 摔倒=slip and fall
和can only be used to connect two nouns but not two verbs or two sentences.
她把手臂摔断了。She broke her arm by falling.
因为没有人帮助她，所以她一个人回家了。Because there was nobody helping her, she went home alone.
今天她的手臂已经好了。Today her arm is already healed (good)。
我非常高兴她的身体好了。I am very glad, that she is feeling better (her body is better)
快乐has more the meaning of "merry"