geleceğim - i will go
can someone give me more simple examples using these?

İşe geleceğim.... i will come to work.
Okula geleceğim.... i will come to school.
Sana geleceğim..... i will come to you.

gelmek .. means come,
Gitmek.. means go.

You use the (y) A ,for duration, like TO
Ofcourse (y) here is buffer

Masaya geleceğim....i will come to table.

-ecek and -acak (-yecek and -yacak after vowels) suffixes are used to express future plans and intentions.

the construction is:

verb + -ecek + personal endings

buraya gelecek
he will come here

mektubu yazacak
she will write the letter

şimdi dinleyeceksin!
and now you'll listen!

in the 1st person singular (I: ending -im) and plural (we: ending -iz) personal endings the "-k-" becomes a "ğ".

senin için yapacağım
i will do that for you

garda buluşacağız
we'll meet at the station

then there is also negation of -ecek and -acak.

negative suffix is -me or -ma. but with -ecek and -acak you will need to add the -y- buffer between the 2 vowels.

verb + -me + -y- + -ecek + personal endings

gelmeyeceksin
you will not come

kalmayacağım
i will not stay

başlamayacağız
we will not begin