Construction of the Kirk of the Canongate, or Canongate Kirk, commenced in 1688 and it was opened for use by the parish in 1691. James Smith was architect and it is estimated to have cost 34,000 merks (largely funded by a bequest from Thomas Moodie of Sauchtenhall).
Prior to 1672, Holyrood Abbey Church was used for worship, but the King had made it a private Royal Chapel and between 1672 and 1691 the parishioners used Lady Yester's Church.
More about the history of the church and churchyard can be read here: https://en.wikipedia.org/wiki/Canongate_Kirk
The kirk is surrounded by a large kirkyard which has been calculated to have 62 tombs, 140 monuments and 150 wall plaques, ledgers, etc Ref: https://en.wikipedia.org/wiki/Canongate_Kirkyard
The entrance is on Canongate. It is best to travel to the kirkyard by public transport. If coming by car, you can park quite conveniently about a quarter of a mile away at Holyrood Car Park on Queen's Drive (just south of the Palace of Holyroodhouse), and walk from there, past the front the Scottish Parliament Building and west along Canongate.