I am a Catholic priest......but er, I am not writing infallibly here!
Nor comprehensively, nor dogmatically. Mass in Spain very much the same as Mass in English.
The parts of the Mass, essentially are
1.
Introduction Sign of the Cross, and greeting by priest, followed by penitential rite, which may include or lead to the "Kyrie" /Lord Have Mercy. In Spanish Señor ten piedad/Cristo ten piedad/Senor ten piedad, repeated in dialogue by priest and people. On Sundays and some feast days there will then be the Gloria. (Everyone will join in.)
2.The first major part of the Mass follows, the
Liturgy of the Word. It is the same the world over, with the same readings, essentially used everywhere, though there can be some local variation for feast days. Everyone will sit down at this point if not already sitting.
There will be a
first reading - can be either a NT letter, or Apocalypse, or in the six weeks after Easter always the Acts of the Apostles, or it can be from the OT.
This is followed by a psalm, to which the people respond between each verse.
On Sundays and major feast days only there will be a
second reading here - in which case the first reading will be OT and the second reading NT.
There is then a brief Alleluia verse.
Then the
Gospel. Everyone in the church will stand for this.
There may be a sermon delivered by the priest after this.
On Sunday there will then be the Profession of Faith/ Credo/I believe in God/ Creo en un solo Dios
There may or not be some prayers/intercessions here to which the people will respond, but let's keep it simple.
3. We then move to the second major part, the
Liturgy of the Eucharist. You will see the priest preparing bread and wine, and washing his hands, leading to the Sanctus/Holy, holy, holy/Santo, Santo, Santo. (Everyone will join in). In Spain people will either stand or kneel for this part of the Mass. The priest then moves to the Canon, the fixed prayers for the consecration of bread and wine. You will see the priest hold up the host and the chalice for the people to see. There are more prayers after this, leading to a common declaration of AMEN - the "great amen".
4. Then we have the
Communion Rite. The people will stand, if they have been kneeling, and recite
together with the priest the Our Father/ Padre nuestro. There are further prayers and the priest will then distribute communion. Just before this, the priest will say The Peace of the Lord be always with you
La paz del Señor esté siempre con vosotros. There MAY be an exchange of greetings in the church at this point, a hug/handshake/or kiss. A handshake and a smile will never be misunderstood here! There is no need to say anything.
5. Thereafter there may be a period of silence and a few concluding prayers and a blessing, the
concluding rite.
So a few landmarks.....
- At the beginning, after a few minutes everyone will sit: this marks the liturgy of the word. People will then stand for the Gospel.
- Then, with people sitting, you will see the priest prepare the offerings at the altar.
- Then you will see the priest raising separately the host and chalice. This is the central moment of the Mass, the consecration. People will be either kneeling or standing at this time.
- Shortly after this everyone will stand and recite together the Lord's Prayer. May exchange a sign of peace after this.
- This will be followed by the distribution of communion by the priest and/or lay ministers.
- Then some concluding prayers.
I don't want to complicate it any more, but ask any questions you wish.
As a general guide, get in a seat behind a "little old lady" and do what she does in terms of posture. And people will not mind if you stand, sit or kneel at the wrong time, even though you may feel everyone is looking at you. They won't be! If you want to sit throughout Mass, I don't think anyone would ever object. particularly if you look a bit dusty and tired.
This may help
https://www.misas.org/sta.tic/descarga/missa_es_en.pdf
There are lots of apps and sites which will give you the readings for the day and
generally Spanish readings will be indentical to the English, if you want to read along. I have got past any embarrassment at being seen looking at my phone during Mass to follow the readings in far flung countries. And no one has ever objected!!!