c.muzah san,
konnichiwa.
Spaces between words should not be put in sentences officially.
When we give sentences for young children, we use sentences including spaces is called wakachi bun.
The reason why is that young children’s vocabulary and grammar knowledge is not limited so wakachi bun helps word boundaries.
Regarding your sentences,
こんにちは。
わたしはChenge です。
ありがとうございます。
please put full stops then they are perfect!
Yuki 由紀
Team JapanesePod101.com