Some snippets:
"A la derecha del rio estaba la division alavesa"
The Alavesa division was to the right of the river (#1 in the sketch map).
"la brigade de vanguardia al mando de Gurrea … la primera que cambio tiros con las guerrillas Carlistas"
The vanguard brigade under Gurrea … was the first to exchange fire with the Carlist guerrillas whose line is #13in the sketch map.
"Espartero se situe en la izquierda del rio"
Espartero's 2nd Division was to the left of the river
"La brigade de don Santiago Mendez Vigo ocupo el centro de la linea con el cuartel general"
Don Santiago Mendez Vigo's brigade was in the centre with HQ (#2).
"Gurrea formo el ala derecha"
Gurrea formed the right wing (#3).
"Don Froilan Mendez Vigo observaba con su brigade para atacar a la de Eraso, situado en Obanos, y un batallon en Artajona custodiaba los bagajes"
Don Froilan Mendez Vigo's brigade (#4) was observing to attack [Eraso's brigade at Obanos?], and a battalion was guarding the baggage in Artajona.
"Lopez, con su caballeria (#5) ocupaba un camino ventajoso entre los caminos de Larrage y Artajona"
Lopez and his cavalry were on an advantageous road between the Larrage and Artajona roads.
"La bateria rodada ocupo el sition marcado con num 11"
The [horse?] battery began the battle at #11 and finished at #12.